.PS
[	A:	ellipse "$D sub 1$"
		arrow down from last ellipse.s
	B:	ellipse fill light "$D sub 2$"
	T:	box fill light "$T sub 1$" with .w at B.e + .2,0
		arrow from B.e to T.w
		arrow dotted from A.se to T.nw
]
[	ellipse "$D sub 1$"
] with .nw at last [].ne + .5,0
.PE
